The Oxygen-Ion Diffusion and Phase Transition in the La2Mo2-xWxO9 Samples Measured by Internal Friction Method

2012 ◽  
Vol 160 ◽  
pp. 8-11 ◽  
Author(s):  
Dan Li ◽  
Xiang Hu Li
Keyword(s):  
Phase Transition ◽  
Internal Friction ◽  
Ion Diffusion ◽  
Oxygen Ion ◽  
Temperature Spectra ◽  
Friction Temperature ◽  
Temperature Relaxation ◽  
Friction Method ◽  
Two Peaks ◽  
Oxygen Ion Diffusion

The effects of tungsten doping on the oxygen-ion diffusion and the phase transition in La2Mo2–xWxO9 samples (x = 0.5, 0.75, 1.0, 1.2) were studied using internal friction method. The results show that two peaks were detected in the internal friction-temperature spectra in the La2Mo2-xWxO9 samples, the low-temperature relaxation peak is associated with oxygen ion diffusion, and the high-temperature peak is associated with a phase transition from the static disordered state to the dynamic disordered state of oxygen ion/vacancy distribution.

Influence of Tungsten Doping in La2Mo2O9 Oxide-Ion Conductors by Dielectric Relaxation Measurements

2011 ◽  
Vol 130-134 ◽  
pp. 3302-3305
Author(s):  
Dan Li ◽  
Xiang Hu Li
Keyword(s):  
Phase Transition ◽  
Dielectric Relaxation ◽  
Ion Diffusion ◽  
Ion Distribution ◽  
Β Phase ◽  
Oxygen Ion ◽  
Relaxation Measurements ◽  
Temperature Relaxation ◽  
Oxygen Ion Diffusion ◽  
Tungsten Doping

The effects of tungsten doping in La2Mo2–yWyO9 (y =0, 0.25, 0.5, 1.0, 1.4) samples were studied using dielectric relaxation measurements. The results indicate that the solubility of W6+ in La2Mo2O9 sample is about 25mol%, W6+ can suppress the α/β phase transition in the La2Mo2O9. Additional to the low-temperature relaxation peak Pd associated with oxygen ion diffusion, a new dielectric loss peak Ph associated with a phase transition from the static disordered state to the dynamic disordered state of oxygen ion distribution was observed around 740 K. The conductivity of La2Mo1.9W0.1O9 sample is higher than that of the pure La2Mo2O9, and then decrease with the increasing of the tungsten doping in La2Mo2–yWyO9 (y = 0.5, 1.0) samples in the whole measurement temperature.

Dielectric Relaxation Measurements in La2Mo1.5W0.5O9 Oxide-Ion Conductor

2014 ◽  
Vol 952 ◽  
pp. 51-54
Author(s):  
Dan Li ◽  
Jun Li ◽  
Chong Chen ◽  
Lin Qi ◽  
Xiang Hu Li
Keyword(s):  
Phase Transition ◽  
Dielectric Relaxation ◽  
Ion Diffusion ◽  
Ion Distribution ◽  
Ion Conductor ◽  
Oxide Ion Conductor ◽  
Β Phase ◽  
Oxygen Ion ◽  
Relaxation Measurements ◽  
Temperature Relaxation

The effects of tungsten doping in La2Mo1.5W0.5O9 sample were studied using dielectric relaxation measurements. The results indicate that W6+ can suppress the α/β phase transition in the La2Mo2O9. Additional to the low-temperature relaxation peak Pd associated with oxygen ion diffusion, a new dielectric loss peak Ph associated with a phase transition from the static disordered state to the dynamic disordered state of oxygen ion distribution was observed around 740 K.

Influence of Fe Doping on the Oxygen-Ion Diffusion and Electrical Conduction of La1.95K0.05Mo2-XFexO9-δ

2010 ◽  
Vol 663-665 ◽  
pp. 506-510
Author(s):  
Chun Li ◽  
Da Li ◽  
Qian Feng Fang
Keyword(s):  
Phase Transition ◽  
Fe Doping ◽  
Conductivity Measurements ◽  
Ion Diffusion ◽  
Solid Reaction ◽  
Ion Conductor ◽  
Reaction Method ◽  
Oxygen Ion ◽  
Oxygen Ion Conductor ◽  
Oxygen Ion Diffusion

Based on the oxygen ion conductor La1.95K0.05Mo2O8.95, a series of Fe-doped samples La1.95K0.05Mo2-xFexO9- (x=0, 0.025, 0.05, 0.1) were prepared with conventional solid reaction method. The effects of Fe doping on the structure, oxygen ion diffusion and electrical conductivity were studied. Based on the results of conductivity measurements, it can be concluded that Fe doping can improve the conductivity obviously, and doping of both Fe and K samples have better conductivity, which successfully suppresses the phase transition.

scholarly journals Oxygen deficient layered double perovskite as an active cathode for CO2 electrolysis using a solid oxide conductor

2015 ◽  
Vol 182 ◽  
pp. 227-239 ◽  
Author(s):  
Tae Ho Shin ◽  
Jae-Ha Myung ◽  
Maarten Verbraeken ◽  
Guntae Kim ◽  
John T. S. Irvine
Keyword(s):  
Double Perovskite ◽  
Cathode Side ◽  
Layered Perovskite ◽  
Ion Diffusion ◽  
Oxide Electrode ◽  
Oxygen Ion ◽  
A Site ◽  
Oxygen Ion Diffusion ◽  
Co2 Electrolysis ◽  
A Current

A-site ordered PrBaMn2O5+δ was investigated as a potential cathode for CO2 electrolysis using a La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) electrolyte. The A-site ordered layered double perovskite, PrBaMn2O5+δ, was found to enhance electrocatalytic activity for CO2 reduction on the cathode side since it supports mixed valent transition metal cations such as Mn, which could provide high electrical conductivity and maintain a large oxygen vacancy content, contributing to fast oxygen ion diffusion. It was found that during the oxidation of the reduced PrBaMn2O5+δ (O5 phase) to PrBaMn2O6−δ (O6 phase), a reversible oxygen switchover in the lattice takes place. In addition, here the successful CO2 electrolysis was measured in LSGM electrolyte with this novel oxide electrode. It was found that this PrBaMn2O5+δ, layered perovskite cathode exhibits a performance with a current density of 0.85 A cm−2 at 1.5 V and 850 °C and the electrochemical properties were also evaluated by impedance spectroscopy.

Werkstoffaufbau und diffusiver Stofftransport aufgezeigt an ausgewählten Beispielen / Material structure and diffusive mass transport as pointed out by means of selected examples

2000 ◽  
Vol 6 (4) ◽  
pp. 429-450
Author(s):  
R. Kriegel ◽  
A. Buchwald ◽  
Ch. Kaps
Keyword(s):  
Mass Transport ◽  
Diffusion Coefficients ◽  
Transport Mechanism ◽  
Diffusion Models ◽  
Second Law ◽  
Material Structure ◽  
Ion Diffusion ◽  
Oxygen Ion ◽  
Oxygen Ion Diffusion

Abstract The diffusive mass transport in materials is above all determined by the material structure. The experimental determination of diffusion coefficients is based on diffusion models, which results from special mathematical solutions of Fick's second law and its corresponding boundary conditions. The general usefulness of these diffusion models will be described using some examples, e. g. the diffusion of deteriorating salts in masonry materials, the oxygen ion diffusion in mixed conducting ceramics and the cation exchange in single crystals. The measurement of the diffusion coefficients results in a better comprehension of the transport mechanism as well as of the "morphology" of the transport medium, which allows to optimize the conditions of the mass transport and the material structure and composition, respectively.

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